The name given to a random person who's name you do not know that somehow gets caught in your conversation and/or argument with another person you know.
From the Seinfeld episode "The Butter Shave" where an innocent passanger seated next to Elaine and Putty on their plane ride back to New York is refered to as 'vegetable lasagna'.
Putty: Oh, tell me about it! I don't know why I ever took you back.
Elaine: Oh please, I took you back! You know it, I know it, vegetable lasagna here knows it!
Vegetable Lasagna: Please, please! I don't want to get involved!
Ruler of Lake Titicaca. Rumored to have a bunghole that gets very angry if it does not receive toilet paper. Cornholio the Great is often seen walking around with his shirt over his head and his hands in the air, chanting songs about his power, and his bunghole.
"I am Cornholio! You do not want to face the wrath of my bunghole, for I need TP!"
Butthead: Shut up, Beavis! (uh huh huh huh)
Beavis: Um, okay. (heh heh heh heh).